Prosthetic Energy Storing and Releasing Apparatus and Methods

ABSTRACT

A prosthetic lower leg uses one or more generally C-shaped spring elements between the patient&#39;s socket and a foot-plate assembly. The respective connections between (a) those one or more elements and (b) that socket and that footplate can be configured to provide a lightweight and economic prosthesis that effectively mimics the feel and performance of a normal human foot. The prosthetic spring element is generally C-shaped, and can have a substantially constant thickness along its length, lending itself to being fabricated by automated processes such as filament winding. One or more of the generally C-shaped spring elements can be incorporated into other prostheses and/or other devices.

This application is based on and claims the benefits of the filing dateof U.S. Provisional Patent Application No. 61/541,041 (filed Sep. 29,2011).

The present invention is described here with reference to theaccompanying Figures, which serve as illustrations of some of the manyembodiments in which the invention may be practiced. Generally in thoseFigures and references (but subject to the context and other factors,including for example the understanding of persons of ordinary skill inthe arts relevant to the inventions), similar reference numerals referto similar or identical elements throughout this description.

Those Figures and references, and the other terminology used in thesedescriptions, are not intended to be interpreted in any limited orrestrictive manner, simply because it is being utilized in conjunctionwith a detailed description of certain embodiments of the invention.Furthermore, various embodiments of the invention (whether or notspecifically described herein) may include one or more novel features,no single one of which (a) is necessarily solely responsible for one ormore desirable attributes of the invention or (b) is essential topracticing the inventions described.

DESCRIPTION OF DRAWINGS

FIGS. 1, 1 a and 1 b are perspective views of a preferred embodiment ofthe present invention having two elongated curvedenergy-storing/releasing members.

FIG. 1c is an elevation view of an overall prosthetic assembly inaccordance with the present invention, including a prosthetic devicehaving two elongated curved energy-storing/releasing members operablyconnected to a prosthetic socket, and having a compressible element.

FIGS. 2, 2 a, 2 b, 2 c, and 2 d are exploded perspective views of anoverall prosthetic assembly in accordance with the present invention.

FIG. 2e is a top view of two elongated curved energy-storing/releasingmembers in accordance with the present invention.

FIGS. 2f and 2g are elevation views of an overall prosthetic assembly inaccordance with the present invention, having a connector element in aforward position (FIG. 2f ) and a preferred position (FIG. 2g ).

FIG. 3a is an elevation view of an alternative embodiment of the presentinvention having a single elongated curved energy-storing/releasingmember and a Z-bar extension portion.

FIG. 3b is an elevation view of an alternative embodiment of the presentinvention having a single elongated curved energy-storing/releasingmember with a swept-back extension portion.

FIG. 3c is an elevation view of an alternative embodiment of the presentinvention having a single elongated curved energy-storing/releasingmember and a toe extension portion of the footplate operably connectedthereto.

FIG. 3d is similar to FIG. 3g , but having an angled bolt for connectingthe toe extension portion to the footplate.

FIGS. 4a, 4b, and 4c show the device of FIG. 3a in roughly heel-strike(FIG. 4a ), mid-stance (FIG. 4b ), and toe-off (FIG. 4c ) positions (theprecise curvature and the smoothness of the curved spring elements mayvary from that shown in this drawing). A vertical line indicates thevertical load as the patient passes through these positions of his/herstride. In the toe-off position, the toe portion of the footplate, the Cspring, and the Z-bar have all been compressed somewhat from thatloading.

FIG. 5a is an elevation view of another alternative embodiment of thepresent invention having a single elongated curvedenergy-storing/releasing member operably attached to the footplate inorder to move the pivot point forward towards the toe portion of thefootplate.

FIGS. 5b and 5c are elevation views of another alternative embodiment ofthe present invention having a single elongated curvedenergy-storing/releasing member operably attached to the footplate,having “diving board” lines to illustrate the benefits of moving forwardthe connection point between the C-shaped spring element and the Z-barmember. As described further herein, locating that connection point ator around line B would provide very little, if any, leverage to thepatient to be able to vertically compress the C-shaped spring. By movingthat connection out toward to toe of the prosthesis, including to and/orbeyond line A, the “diving board” is lengthened, allowing the patient tomore easily compress the C spring and other elements (and enjoy the softtransitions provided thereby) in the vertical direction.”

FIG. 6a is an isometric view of a stack of multiple energy storing andreleasing elements fabricated by a filament winding process.

FIG. 6b is a perspective end view of the stack of energy storing andreleasing elements shown in FIG. 6 a.

FIG. 6c is a perspective elevation view of the stack of energy storingand releasing elements shown in FIG. 6 a.

FIGS. 6d and 6e are perspective views of multiple energy storing andreleasing elements fabricated by a filament winding process.

FIG. 6f is a top view of the multiple energy storing and releasingelements shown in FIGS. 6d and 6 e.

FIG. 6g is an isometric view of a single energy storing and releasingelement fabricated by a filament winding process.

FIGS. 6h and 6i are perspective views of the single energy storing andreleasing element shown in FIG. 6 g.

FIG. 6j is an elevation view of the single energy storing and releasingelement shown in FIG. 6 g.

FIG. 6k is a side view of the single energy storing and releasingelement shown in FIG. 6 g.

FIG. 6l is a bottom view of the single energy storing and releasingelement shown in FIG. 6 g.

FIG. 7 shows a top and side view of a preferred C-spring element inaccordance with the present invention, and a top view of the ends of theC-spring element with holes for connecting the C-spring element at aconnection point(s).

FIG. 8 is a perspective view of composite laminate layers in accordancewith the present invention.

FIG. 9 is a section view of an upper connector in accordance with thepresent invention.

FIGS. 10a, 10b, 10c, 10d, and 10e are front, back and side perspectiveviews of a connector element having swivel features assembled with adouble C-spring device in accordance with an embodiment of the presentinvention.

FIGS. 10f and 10g are perspective views from below and above of ashortened and unassembled connector element having swivel features inaccordance with an embodiment of the present invention.

FIG. 10h shows standard views of a connector element having swivelfeatures in accordance with an embodiment of the present invention.

FIGS. 11a, 11b, 11c, and 11d are front, rear and side perspective viewsof an overall prosthetic assembly in accordance with the presentinvention, including a prosthetic device having two elongated curvedenergy-storing/releasing members.

FIG. 11e is an elevation view of an overall prosthetic assembly inaccordance with the present invention, including a prosthetic devicehaving two elongated curved energy-storing/releasing members operablyconnected to a prosthetic socket, and having a “diving board”connector/spring element.

FIG. 11f is an elevation view of an overall prosthetic assembly inaccordance with the present invention, including a prosthetic devicehaving two elongated curved energy-storing/releasing members operablyconnected to a prosthetic socket, and having a double bladdercompressible element and strap.

FIG. 12a is an elevation view of an overall prosthetic assembly inaccordance with another embodiment of the present invention, including aprosthetic device having a single elongated curvedenergy-storing/releasing member, an alternate upper connector element,and an alternate lower connection portion.

FIGS. 12b, 12c, 12d, 12e, 12f, 12g, 12h, 12i, and 12j are perspectiveviews of another embodiment of the present invention having a singleelongated curved energy-storing/releasing member and a Z-bar extensionportion.

FIGS. 13a, 13b, and 13c are perspective views of a C-spring inaccordance with a preferred embodiment of the present invention.

FIGS. 14a and 14b are side views of a bladder element in accordance withan embodiment of the present invention. Persons of ordinary skill willunderstand that the side views of both single and double (and triple,etc.) bladder embodiments will be the same regardless of whether theyhave a single tube or more (so long as the other tubes are positionedlaterally behind the “front” one that shows in the drawing).Accordingly, these drawings illustrate bladder embodiments having atleast a single (or more) bladder and a single (or more) tubes.

FIG. 14c is an end view of a single bladder having a single tube inaccordance with an embodiment of the present invention.

FIGS. 15a, 15b, and 15c are isometric views of a double bladder havingdouble tubes in accordance with another embodiment of the presentinvention.

FIG. 15d is an isometric section view of the double bladder embodimentshown in FIGS. 15a, 15b , and 15 c.

FIG. 15e an end view of the double bladder embodiment shown in FIGS.15a, 15b , and 15 c.

FIG. 15f is top view of the double bladder embodiment shown in FIGS.15a, 15b , and 15 c.

FIGS. 16a and 16b are isometric views of a double bladder having asingle tube in accordance with another embodiment of the presentinvention.

FIG. 16c is a bottom view of the double bladder with single tubeembodiment shown in FIGS. 16a and 16 b.

FIGS. 16d and 16e are end views of the double bladder with single tubeembodiment shown in FIGS. 16a and 16 b.

FIG. 16f is a top view of the double bladder with single tube embodimentshown in FIGS. 16a and 16 b.

FIGS. 16g, 16h, 16i, and 16j are isometric section views of the doublebladder with single tube embodiment shown in FIGS. 16a and 16 b.

FIGS. 17 through 25 are elevation views illustrating some of the manyother various combinations and permutations that can be used to practicethe invention. Among other things, they generally show the use of morecompletely circular embodiments of spring elements. This use of morecompletely curved springs can be accomplished in a wide variety of ways;as shown, the adapters that connect the upper and/or lower ends of thespring elements are configured to include a matingly curved contactsurface that at least approximates the relevant curvature of the springelement. They also show the use of supplementary spring elements, energystoring/releasing foot and/or toe elements to further refine and enhancethe performance of the prosthesis, straps/restraints to limit thedeformation of the prosthesis, and cushion/bladder elements to smooththe transition of energy loading and release.

The aforementioned single spring embodiment with the separate toesection preferably includes a non-tapered relatively thin toe plate.Also preferably, and as shown for example in FIG. 25, the toe plateextends behind the lower/heel bolts (or other connection between theupper C spring and the heel/foot plate) and has a restraining strap orother restraining means at its heelward end, which provides ampleoperational/bending length for the desired toe action. This preferredbending assembly thus combines the performance of a long “diving board”(a long forward attachment position for the main C spring, as discussedelsewhere herein) with a desirable operational bending energy storingspring as a toe element.

FIG. 26 is an overlay of two of the embodiments from the other drawings,for comparison purposes. In FIG. 26, the sockets at the top of the twodrawings have been generally aligned, allowing a comparison of the lowerportions of the two prostheses. Among other things, this illustrates howslight modifications to curvature, orientation, and other factors can beused to produce embodiments of the invention that can be used fordifferent amputees and for different purposes and activities.

FIG. 27 is similar to FIG. 26, but instead of aligning the sockets, thespring elements are generally aligned, and the differences in thepositioning and orientation of the socket elements can be seen.

FIG. 28 illustrates a “double spring” embodiment with the morecompletely curved spring elements shown in FIGS. 17-25.

FIG. 29 shows a “land mine foot” that includes various of the foregoingelements, including the more completely circular spring elements, afootplate, various straps/restraints to limit the deformation of theprosthesis, and a cushion/bladder element to smooth the transition ofenergy loading and release.

DETAILED DESCRIPTION OF EMBODIMENTS

The present inventions preferably include and/or constitute one or moreelongated energy storing and releasing elements, usable in lower legprostheses and other devices and assemblies and methods. In addition,the inventions preferably include various methods of fabricating,assembling, fitting, and otherwise using various prosthetic devices,including devices having single and/or multiple elongated energy storingand releasing elements.

The particular materials, dimensions, and fabrication methods forpracticing the invention can be selected from a wide range ofpossibilities, depending on a number of factors (including thosediscussed in many of my previous patents, which are incorporated hereinby reference). By way of example, these energy storing and releasingelements can be formed by any suitable method(s) and from any suitablematerial(s), including from resin-impregnated fiber, and by filamentwinding processes, among others.

Preferably, the invention is practiced in a modular manner, so that thevarious components (e.g., footplates, connectors, extensions, bolts,C-Shaped Spring elements, and others) are effectively interchangeablewith other such components, and may sometimes even be interchangeablebetween various Single Spring, Two-Spring, and other embodiments of theinvention. These components may even be used in retrofitting existingdevices. This enables easy customization, maintenance, and repair of anoverall prosthetic assembly 50. Depending on the patient and theapplication, certain components may need to be shaped slightlydifferently for cosmetic or other reasons, but their functionalitypreferably is at least substantially unaffected by such changes.

Although the energy storing/releasing member(s) 5 and other parts of theassembly preferably are modular, they can be fabricated in othercombinations and sub-combinations, and can be relatively permanentlyassembled or otherwise utilized, all without departing from the spiritand scope of the invention.

On another aesthetic point, certain of the embodiments below aredescribed as preferably having the connector/attachment/pivot pointsmoved relatively forward toward the toe portion of the prosthesis.Persons of ordinary skill in the art will understand that this may makeit more difficult to fit a conventional cosmetic cover and/or a shoeover the prosthesis. However, the relatively forward pivot/connectionelements preferably actually can provide some aesthetic benefit. Amongother things, those forward elements preferably hold a normal trouser orpant leg out to a “normal” draping position, forward with respect to thewearer's ankle area (or away from the wearer's heel). Without thosefurther-forward features, the pant leg can be pushed abnormally far backby wind resistance or similar force.

Preferred Use in a Lower-Leg Prosthesis

When incorporated into a lower leg prosthesis, the one or moreenergy-storing/releasing members of the invention and other aspects ofthe invention can provide an excellent experience for wearers, includinga very smooth and natural stride during walking, running, and similaractivities. The Figures and description here focus on examples ofprostheses with one and with two such members, but the presentinventions may be practiced in other combinations of elements (and otherembodiments of prosthetic devices having one- and two-member, or evenmore such members).

In this description and the related Figures, the cadence of walking andsimilar activities is described as including the positions of heelstrike, then mid-stance, and finally toe-off. Persons of ordinary skillin the art will understand that these are not intended as precise andlimiting concepts but instead as a useful framework within which todescribe the invention. Among other things, persons of ordinary skill inthe art will understand that the inventions will find utility in a broadrange of activities other than walking.

Double C Embodiments (Springs 1 and 2)

A preferred embodiment of the invention is illustrated in FIGS. 1, 1 a,1 b, and 1 e as having two of the elongated curvedenergy-storing/releasing members Sa, Sb of the invention 10. As used inthis description of those drawings, “Spring 1” refers to the radiallyoutermost member Sa (located toward the rear of the prosthesis, in theheel area 20 in the drawings), and “Spring 2” refers to the forward or“radially inner” spring Sb. In certain embodiments, Spring 1 Sa isrelatively soft to allow ready vertical compression, and Spring 2 Sb isrelatively stiff, so that it does not allow such ready verticalcompression. Persons of ordinary skill in the art will understand thatthese differences in stiffness and performance characteristics can beachieved by any suitable means, including by varying the number of pliesor other material impregnated into each of those respective Springs 1and 2, and that because of the nature of certain embodiments of theinvention (such as for those in which the C-shaped springs are madeusing resin-impregnated fiber), the springs may be very similar visually(having substantially similar thicknesses, for example) but yet havenoticeably different loading/spring/performance characteristics.

Preferably, both Spring 1 and Spring 2 are operably connected to thepatient's socket 40 at or near their upper ends. This is discussedfurther below in connection with a preferred connector element 35, andis illustrated in the drawings as being accomplished by a single boltplaced through holes in both Spring 1 and Spring 2 and then through aball/sphere support structure that rotatably seats in a confrontingsocket (not the “socket” into which the patient places his/her stump) onthat connector, and through a corresponding hole in that connector. Toallow a wide range of angles and orientations at that connection point,various washer elements are provided and at least the hole through theconnector element opens to an increasingly larger radius in the generaldirection of from the patient toward the prosthetic toe portion 25.Persons of ordinary skill in the art will understand that (a) thisallows a convenient adjustment and alignment of the prosthetic assemblywith respect to the patient (as further discussed below) and (b) manyother alternative attachment structures can be used without departingfrom the scope of the invention. By way of example, each of Spring 1 andSpring 2 can be separately connected to the patient's socket, ratherthan being joined in a common connection point.

As shown in the drawings, the lower end of Spring 1 preferably isattached to a middle portion 30 of the footplate 15, and in a restingposition, the lower end of Spring 2 preferably is spaced above thefootplate and relatively forward (toward the toe portion) from thatSpring 1 connection point.

As indicated above, preferably both Springs 1 and 2 are fabricated andconfigured to be capable of energy storage and release as the patientwearing the prosthesis undertakes various activities (such as walking).Preferably, the spring/bending properties of both Springs 1 and 2 urgethem to their resting “C” position 100 from either an expanded condition(a more open C) or a compressed condition (a more closed C). Anytwisting or other deformation of the elements such as Springs 1 and 2likewise preferably stores that twisting/other energy and urges thespring element to return to its untwisted “resting” position.

Preferably, Springs 1 and 2 are oriented so that their respectiveC-shaped portions open toward the front of the wearer. This preferablyallows the prosthetic assembly to be enclosed in a cosmetic cover andotherwise fit within the profile of a natural foot and into conventionalshoes. In some of the many alternative embodiments of the invention,however, the Springs (especially the interior Spring 2) can be rotatedabout a generally vertical axis through their upper and lower connectionlocations, at 180 degrees (so that it opens toward the wearer's heel) orat some other angle, and still provide some or all of the benefitsdescribed herein. However, such alternative angles presumably would makeit difficult to use a conventional cosmoses over the prosthesis.

Heel Strike

Within the walking cadence terminology mentioned above, “heel strike”refers to that portion of a normal forward stride that includes theinitial contact of the heel with the ground or other surface. Asdiscussed below, the continuation of the stride moves the prostheticfoot from heel strike toward the mid-stance position.

In many embodiments, a prosthetic footplate 15 is operably affixed tothe lower end(s) of the C-shaped spring members. Although the inventionpreferably can be practiced with a wide range of sizes and shapes of thefootplate (and variations in other features, such as whether it is asingle piece or formed from separate heel and toe elements, orotherwise), a convenient and conventional size and shape for suchfootplates is generally flat, in the shape of the sole of a naturalfoot, including having a toe portion and a heel portion. Preferably, allor most of the prosthetic footplate is also fabricated as a deformableenergy storing/returning element, via filament winding or hand layup orother process.

Just prior to heel strike, as the wearer is stepping forward, thefootplate preferably is angled upwardly (approximating the position of anatural foot), with the toe portion at least slightly higher than theheel portion. This means that, at heel strike, the footplate's heelportion preferably is the first part of the footplate to contact theground or other surface (thus the term “heel strike”).

As the patient moves forward through the heel strike position andportion of the stride, the heel portion may deform slightly (storingenergy that will be released in later stages of the stride) and anincreasing area of the preferred footplate member heel portionpreferably contacts the ground or other surface. At least in part, theheel portion deformation or bending is caused by the wearer starting totransfer his or her weight onto that prosthetic heel/foot.

In addition to and/or independently of the heel deformation, thattransfer of the patient's generally vertical weight loading preferablyimmediately engages and begins compressing Spring 1 (again, storingenergy that will be released in later stages of the stride). Spring 1preferably is sufficiently “soft” or energy-compliant that Spring 1immediately, gradually, and smoothly begins to compress and store thatenergy, for subsequent spring-back action. As the wearer continues intothe step and puts more weight onto that leg/foot, Spring 1 continues tocompress and thereby store increasing amounts of energy. In manypreferred embodiments, the compression of Spring 1 is on the order ofapproximately one inch of vertical compression for a 3G vertical load.

As indicated above, the heel strike condition and portion of the stridemay bend the heel portion of the footplate relatively upward toward theC-shaped portion(s). The existence of such deformation and its amountand other characteristics can depend on a number of factors (forexample, the nature of the loading on the prosthesis, the springcharacteristics of Spring 1, the spring characteristics of thefootplate, and others). Because the toe portion of the footplate is notyet contacting the ground during heel strike, the heel strike loadingpreferably also tends to pivot the footplate around the connection pointbetween Spring 1 and the footplate, causing the toe portion of thefootplate to plantar-flex (the toe portion is pushed toward the ground).If unchecked, the toe portion might even immediately (and undesirably)“slap” down onto the ground/surface.

Because Spring 1 preferably is relatively so “soft” (to provide thedesired vertical compliance), Spring 1 provides relatively little, ifany, resistance to that planter-flexion. Instead, a preferred embodimentof the device relies on the inner C (Spring 2) to help limit thatplantar-flexion. Preferably, the inner C (Spring 2) is relativelystiffer than Spring 1, and is operably connected at its upper end to theupper end of Spring 1, and at its lower end to the toe portion of thefootplate (via a strap 65 or other means, as further discussed herein).

In a preferred configuration, the plantar-flexion of the footplate's toeportion also pulls the strap member 65 toward the ground, and the strapin tum imposes a load on Spring 2. This load urges Spring 2 to “open”into a larger C shape, and depending on the loading and the springcharacteristics of Spring 2 and other factors, permits some desirableamount and rate of plantar flexion. As it opens/spreads, Spring 2preferably stores that energy (proportional to the amount of thatexpansion), which energy begins urging the toe portion back toward itsresting unloaded position relative to the other prosthetic elements.

In various embodiments, and depending on factors such as the loadingconditions on the prosthesis, Spring 2 can be so stiff that it does notflex open from its rest position—it instead just acts as a “stop” forplantar flexion/toe loading. Preferably, however, Spring 2 provides somedegree of gradual and smooth transition from (a) relative movement ofthe toe portion away from the C-shaped springs 1 and 2 (plantar flexing)to (b) no further relative movement or plantar flexing (the toe portionis no longer moving “away” from the C-shaped springs).

Thus, during a preferred normal heel strike, while Spring 1 is beingcompressed as the patient shifts weight onto the prosthesis, the inner C(Spring 2) is being expanded because of the plantar flexion of the toeportion of the footplate. As explained below, the opposite conditionpreferably exists during the toe off/toe loading portion of the wearer'sforward stride: at least the inner C (Spring 2) preferably is being“closed/compressed” into a more tightly curved shape than itsnormal/resting shape, and the outer C (Spring 1) may be expanded/openedbeyond its normal/resting shape, from being pulled open by the heelportion of the footplate being flexed away from the C spring(s). In bothof these conditions, the prosthetic assembly preferably stores energythat will urge the assembly back into its normal/resting configuration.As also described herein, the preferred uniform thickness and generallysmooth curved shape of Springs 1 and 2 make the variousloading/unloading conditions feel very smooth and natural to the patientas he or she moves through his/her stride.

Mid-Stance

Mid-stance can be described as the patient's normal standing/restingposition, with the footplate in a generally flat and unbent position.

As the wearer continues his stride from heel-strike and approaches andmoves into mid-stance, the softness of Spring 1 allows it to gentlycompress and cushion the patient's impact on the ground or othersurface. Eventually, that compression preferably reaches a point wherethe wearer's weight preferably begins to at least somewhat verticallycompress Spring 2. Among other things, this vertical compression“preloads” or stores energy in the inner C Spring 2, which energy canlater help the patient during other portions of the wearer's stride(such as toe-off) or other movements.

To achieve this desired pre-loading of Spring 2, some vertical forcemust be transmitted between the ground and the lower front end of Spring2. A wide range of structures and methods can be used to accomplish thisenergy transmission, including preferred embodiments that have one ormore compressible elements 55 positioned between the lower/frontportions of Spring 2 and the toe portion of the footplate. Thesecompressible elements can be fabricated from any suitable material andcan be in any suitable shape and position within the prostheticassembly. Preferred examples include bladders (which can be filled withair, liquid, or other substances), rubber or foam elements 60, rodsinserted or insertable into other elements, solid/flexible/spring-actionconnecting members, combinations of these or other elements that arerelatively softer/harder (or even incompressible), and others.

Preferably, the compressible member(s) between the toe portion of thefootplate and the front lower end of Spring 2 provide one of severalways to adjust or fine-tune the performance of the prosthesis. By way ofexamples: the compressible member(s) can be multiple pieces (of foam orother materials or combinations); each compressible member can havedifferent stiffnesses/durometers; the member(s) can be manufactured orotherwise provided with a graduated or variable stiffness across thecompression movement; and the members preferably are provided inmodular/interchangeable forms. Multiple compressible elements incombination can provide greater flexibility for adjusting/fine-tuningthe performance characteristics of the prosthesis, especially if eachbladder or other element in the combination is independently adjustable.

In a preferred embodiment, one or more bladders can be filled with air,nitrogen, argon, or other suitable substance, and placed between thelower ends of the spring elements. If the bladders (or any of them) arein sealed (non-adjustable) form, the performance characteristics of theprosthesis still can be adjusted, such as by interchanging and/orrelocating the bladders. Alternatively, one or more of the bladders canthemselves be adjustable, so that a prosthetist or user can make thebladder harder or softer by injecting or removing substance from insidethe bladder (via a valve or other suitable mechanism). For example, thebladders can be provided with adjustment tubes to adjust the resultingpressure inside the bladder, thereby fine-tuning the performance of theprosthesis (adjusting the vertical stiffness, toe load, etc.).

In certain embodiments, as the wearer moves through midstance andapproaches toe off, the one or more compressible members may be exposedto frictional or similar forces between (1) the bladder(s) and (2) therespective contacting portions of Spring 2 and the footplate. Suchforces can occur during walking, for example, as the forward/lower endof inner Spring 2 moves forwardly (or tries to move forwardly) withrespect to that toe portion (such as may occur as the wearer movestoward toe-off). This rolling/sliding frictional force is reversedduring “unloading” of the energy storing springs, footplate, and/orother elements of the prosthesis. Under these conditions, theforward/lower end of inner Spring 2 moves backwardly with respect to thefootplate.

A preferred embodiment provides the compressible members in a“scuba-tank” shape, generally oriented parallel to the ground andtransversely to the heel-toe axis of the foot. One or more such “tanks”can tend to roll between the other prosthetic spring elements as thewearer walks. Even if the compressible elements are in some other shape(not a tube/tank) that is relatively flat and therefore not especiallysusceptible to rolling, the relative movements and/or deformations ofthose prosthetic components can impose “sliding” frictional forcesbetween those elements.

Although the invention can be practiced even if such rolling/slidingoccurs, in preferred embodiments the rolling action is reduced oreliminated by means such as by shaping the compressible element(s) topreclude rolling, anchoring the compressible element(s) at a specificlocation (using glue or other means), adding tabs or other structures toblock any such rolling, or any other suitable means. In a preferredembodiment, two or more such tube/tank-shaped bladders or other elementsare formed integrally with each other (such as affixed to each otheralong one side), so that the effective overall shape of thecombined/attached tanks is more “flat” and less likely to roll. Insteadof or in addition to such shaping, “stops” or similar features can beprovided in any suitable manner, including being formed into one or moreof the various pieces (the compressible elements, the footplate portion,the underside of the lower front surface of Spring 2, and/or acombination of those) and/or glued or otherwise attached/affixed atappropriate locations. In alternative embodiments, the rolling forces onthe compressible members can be reduced or even eliminated bylubricating those interfaces to facilitate slippage between thosecontacting surfaces. Other approaches to reduce/eliminate that frictioninclude forming and/or coating the contacting surfaces with one or morevery low-friction materials.

As indicated above, a preferred embodiment also includes a loop or strapelement around (a) the compressible members such as “scuba tanks” orfoam, and (b) the lower front end of Spring 2 and the footplate portionthat underlies the compressible members. Among other things, such aconnection enables Spring 2 to help limit the plantar flexion of thefootplate's toe portion.

Thus, some preferred embodiments of the invention provide effective“contact” and energy/movement transmission between the front/lower endsof Springs 1 and/or 2, through an intermediary zone/apparatus (such ascompressible bladders, foam, and/or other elements). In addition topre-loading Spring 2, this intermediary zone/apparatus can provide otherdesirable functionality. For example, the effective connection throughthat intermediary zone/apparatus can provide some resistance to (and/orlimit or even preclude) sideways movement (to the patient's left orright) of the lower end of Spring 2 with respect to Spring 1 and/or thefootplate. Among the many alternative compressible members that can beused in practicing the invention, and as illustrated in FIG. 11e , thefoam/bladder/other elements can be replaced by (or used with) a “divingboard” connector/spring element which is positioned between the toeportion of the footplate and the lower/front surface of Spring 2. Inpassing, the reader will note that the terminology and concept of a“diving board” is also used below in describing certain Single C-Springembodiments of the invention. Persons of ordinary skill in the art willunderstand that use of that term (“diving board”) in connection withthose Single C-Spring embodiments is similar but not necessarilyidentical to the way the term is used here to describe this type ofconnector/spring element in this Double C-Spring embodiment.

As with the other preferred structural elements in this Double C-Springembodiment, this “diving board” connector also preferably is fabricatedas an energy storing and returning element. Preferably, the “divingboard” connector element is relatively stiff. Functionally, the “divingboard” is similar to embodiments using foam/bladder/other elements, inthat it communicates forces (plantar flexion and/or compression, etc.)between the footplate and the front lower end of Spring 2, helps preventexcessive plantar flexion of the toe portion of the footplate, andgenerally supports and smoothes the action of toe loading conditions.Preferably, the amount of stiffness or energy stored/released isproportional to the amount of deformation of the “diving board” element,and at midstance, the preferred “preload” on Spring 2 forces the divingboard to bend slightly from its resting position toward the footplate.

However, as compared to compressible bladders or foam elements, thediving board preferably can be a simpler and longer-lasting approach. Itcan be easier to manufacture and assemble, and have fewer parts, and bemuch less susceptible to wearing out. The diving board does not requirethe external wrapping or similar preparation that may be useful for anycompressible foam elements, it has no bladders that can leaks orotherwise lose pressure, and it does not require any strap element(which, among other things, may break or come loose).

A diving board type of connector/compressible element can be provided ina wide range of sizes and shapes, can be fabricated from a wide range ofsuitable materials, and can be operably connected to the other elementsof the prosthesis in a wide variety of ways. A preferred embodiment isfabricated from graphite that preferably can last for the life of theprosthesis (without wearing out or breaking). The diving board can be atleast partially filament wound or can be fully hand laid up. It alsopreferably has relatively constant thickness, is very thin andlightweight, and has material memory characteristics that provide atleast some additional “spring” action/energy storage/release to theassembly. As compared to a strap for limiting the maximum distancebetween the footplate toe portion and the lower forward end of Spring 2,a diving board type of element can allow some gradual “flex” up to andbeyond the “absolute” limit that might be imposed by a strap.Preferably, from whatever “spread” relationship that is imposed on thosetwo parts (the footplate toe portion and the lower forward end of Spring2), the diving board's energy storing characteristics then urge the toeplate and the lower end of Spring 2 back toward each other (and towardtheir respective resting/non-loaded positions).

More generally, this preferred intermediary zone/apparatus(bladders/foam/diving board/other) preferably enhances the smoothtransition of loading/unloading forces during use of the prosthesis. Thezone preferably provides a very smooth “handoff” of the energy loadingon the prosthesis, such as a smooth transmission from heel strike (whichprimarily loads Spring 1 in vertical compression with Spring 2preferably expanding as it limits plantar-flexion, as discussed above)to the loading involved in midstance, and from there to the toeloading/toe off condition (discussed below).

Alone and/or in combination, these elements and the resulting prostheticassembly preferably help ensure that the patient feels little, if any,sudden change during the course of the complete stride cadence.Preferably, the load of the wearer's weight and other forces smoothlytransfers from and among Spring 1, Spring 2, and any other components ofthe prosthesis. Preferably, as each of those members start to becompressed and/or expanded, they ramp up or increase in stiffness(resistance to further compression/expansion). Although initialdeformation of at least certain of the energy/storing spring memberspreferably is relatively soft and easy (for example, Spring 1),increasing deformation results in increasing stiffness. Preferably, theprosthesis allows some smooth and gradual vertical compression as thepatient moves from heel strike to mid-stance and then to toe-off (theamount and rate of that compression will depend on a number of factors,such as the speed and vigor with which the patient is walking, etc.). Inpreferred embodiments, the various spring members (e.g., Spring 1, 2,and/or 3 et al., the diving board, the footplate, etc.) gradually andincreasingly slow that compression and the other dynamic motions of theassembly. Depending on the embodiment and the patient's use of theprosthesis, the spring elements may eventually reach a point at whichthey do not compress or expand any further (they are “fully” compressedor expanded). Preferably, even the foam/air/bladder/other compressibleelement(s) between the lower front ends of the springs exhibit this samecharacteristic of “ramping up” in stiffness as those elements areincreasingly compressed.

Toe-Off

Toe-off can be described as the part of the stride cadence at which thetoe portion of the footplate is the primary or only portion of theprosthesis that contacts the ground.

Among other situations, toe-off occurs as the patient walks forward frommid-stance onto the “ball” area of the foot and eventually raises thefoot prosthesis completely off the ground. During this movement towardsand through toe-off, the prosthesis preferably provides increasingresistance to dorsiflexion (movement of the toe portion of the footplatetoward the natural leg's shin area). As such dorsiflexion increases, thefoam/air/bladder/diving board/other compressible element preferablyapproaches and even reaches a “maximum” compression, and the toe loadincreasingly is transferred (through that fully-compressed bladder/etc.intermediary zone/apparatus) from the toe area of the footplate toSpring 2.

In conditions in which the compressible element(s) and the toe area ofthe footplate cannot further bend upwardly toward Spring 2 and/orcompress, any further toe loading preferably will result in directcompression of Spring 2, and thus Spring 2 will thereafter provideincreasing resistance to increasing dorsiflexion. Preferably, Spring 2takes most of the toe load as the wearer moves through this toe-offposition.

As the wearer approaches and reaches toe-off, the loading of Springs 1and 2 preferably is reversed from the heel strike condition describedabove. All or most of the vertical load is imposed on Spring 2,compressing it into a tighter arc, while the footplate tends to pivotaround that front connection point, lowering the heel portion of thefootplate and thereby pulling Spring 1 toward a relatively more openposition. To the extent that Spring 1 is “opened” beyond its normalresting position, the energy stored in Spring 1 (by the patient havingforced it “open” during his/her stride) preferably is available to pullthe heel portion back toward its resting position once the prostheticassembly is lifted from the ground (or at least the toe loading isreduced/removed).

As previously indicated, the invention can also be practiced in a widevariety of “multiple C Spring embodiments”, including those having morethan two C-spring elements. Among many other embodiments, a third(and/or a fourth, etc.) spring can be nested in a pattern similar to theway that Spring 2 is nested within Spring 1. The front end(s) of suchsprings can be positioned and operably “connected” to the footplateand/or each other (such as via compressible members, diving boards, orother means), and the particular bending and energy-storing/releasecharacteristics can be customized to provide alternative (and evensmoother) energy transitions for the prosthesis and for the patient'scomfort and experience when walking/etc.

Even for 2 C-Spring embodiments, the invention permits a wide variety ofapproaches from which prosthetists and patients can select. For example,in certain applications, it may be useful for the two or more C-springsto have similar or even identical bending characteristics. Rather thanSpring 1 being significantly “softer” and more easily compressible thanSpring 2, those springs can each have a springiness near or at theaverage springiness of the soft Spring I and stiff Spring 2 embodiments.Persons of ordinary skill in the art will understand that suchalternative embodiments may result in various design and performancecompromises, such as the resulting patient experience during walking orother movement on the prosthesis, the weight and/or complexity of theprosthesis, etc.

Single C (Only Spring 1)

Although there are many similarities between the foregoing preferredDouble C spring (two or more springs) description and preferredembodiments using only a single C spring, there are differences. Forexample, for the same patient changing from a Double C spring embodimentto a Single C spring embodiment (and for the same expected activitylevel and loads), the relatively softer C spring (Spring I of the 2-Cembodiment discussed above) could not be used effectively by itself. Inother words, a preferred Spring 1 in the 2-C embodiment would be toosoft to function well without the relatively stiffer Spring 2 acting asits backup. Among other things, that “softer” Spring 1 would not providesufficient vertical support to the patient, and would not permit thepatient to control the prosthetic footplate satisfactorily.

Instead, for embodiments of the invention that use a single C-spring(rather than the double C or more embodiments discussed above) betweenthe patient's socket and the footplate, to function well that singlespring must be stiffer than the preferred soft Spring I described abovefor the double C embodiments.

Prior to the invention, a prosthesis with a singleenergy-storing/releasing member connecting the patient's socket to themiddle of a heel-to-toe footplate was less than satisfactory. Amongother things, the single energy-storing/releasing member had to be stiffenough to limit both plantar flexion and dorsiflexion of the footplate'stoe and heel portions. As a consequence of being so stiff, the singleenergy-storing/releasing member typically could not provide much, ifany, desirable vertical spring compliance action (energy storing/releasesuch as occurs in the C-shaped springs of the invention). Said anotherway, such prostheses could not provide to the patient any significantamount of vertical “spring” without reducing the patient's ability tosufficiently control plantar flexion and/or dorsiflexion of thefootplate portions. Thus, using the comparison above, if a prosthetisttook a patient's relatively “soft” Spring 1 (from a two-spring designsuch as described above, that was satisfactory to a given patient) andassembled it into a single C lower-leg prosthesis for that same patient,the prosthesis would provide substantial vertical “spring” action to thewearer but would not be sufficiently stiff to provide satisfactoryperformance regarding plantar flexion and/or dorsiflexion, or otherfootplate and/or toe load performance/characteristics.

In contrast, and as described herein, single C-spring embodiments of theinvention preferably emulate a normal foot's heel strike, mid-stance,and toe-off, preferably by combining some or all of the followingfeatures:

-   -   1. a footplate element 15 that approximates the shape and size        of the patient's normal sole, with a toe portion 20 and a heel        portion 25 having material memory (to return to its original        shape) or otherwise capable of spring action energy storage and        release. The footplate can even be a relatively conventional        prior art modular footplate, and it preferably is        fabricated/configured to have bending/spring characteristics        that complement those of the other components or portions of the        prosthesis.    -   2. a single generally C-shaped spring element 70 or portion        positioned between the patient's socket and the footplate        element.    -   3. an extension portion extending upwardly and forwardly        from (a) the approximate middle of the top surface of the        footplate to (b) the forwardmost lower portion of the C-shaped        spring portion. Among its many embodiments, the extension        portion can be integrally formed with the C-shaped spring        portion (such as the “swept-back” 80 example discussed herein),        a separate modular element (such as the “Z-bar” 75 example        discussed herein), or some other suitable structure and        configuration. Preferably, the extension portion also is capable        of spring action energy storage and release.    -   4. The elements between the footplate and the patient's socket        (such as the C-shaped spring portion and the extension portion)        preferably are sufficiently stiff to allow the patient to        desirably control of the footplate and its dorsiflexion and        plantar flexion. However, the extension portion moves the        effective pivot point (of the forward lower end of the C-shaped        spring portion) forward toward the toe area, which (among other        benefits) gives the patient a much longer effective lever arm        for actuating the C-shaped spring portion and the heel portion        of the assembly, and also positions that forward pivot point so        that it can act as a “backstop” for any upward bending of the        toe portion of the footplate (thus enabling embodiments to use        thinner and/or lighter toe portions than would otherwise be        possible). The mechanical advantages of this relative        positioning of the forward pivot point allows the energy        storing/releasing characteristics of the various elements to        substantially mimic the performance of a natural foot and        substantially improve the patient's experience.

To help provide both the desired vertical spring action/compliance andthe desired control over and sensations from toe and heel loading andmovements, preferred single spring member embodiments of the inventionpreferably have a pivot axis for vertical loading that is (a) at or nearthe bottom forward portion of that single C-spring shape, and (b)forward of the middle of the footplate, toward the toe portion of thefootplate (in fact, the further forward that pivot point is located overthe toe portion, the more vertical spring action is available to thepatient).

As described below, that forwardly positioned pivot axis is heldrelatively stiffly in its position with respect to the footplate (toprovide the desired control of the footplate). In fact, the entirelength of the single C-shaped element preferably is substantially stiff(certainly stiffer than the preferred Spring 1 discussed above), but asfurther explained below, the forward positioning of that Single Spring'smain pivot axis provides sufficient leverage to the patient so that itis much easier to deform/compress the preferred “single C” shape.Consequently, although the single C-spring preferably is substantiallystiff along its length, the assembled prosthesis feels to the patient asif it is substantially “soft,” in that it provides to the patient adesirable amount of vertical spring action/compliance. Thus, while thepreferred C-shaped spring portion and the extension portion are stiffenough to provide desired control to the patient, the leverage providedby moving forward the pivot point allows the patient to comfortablyactuate and experience vertical compression of the assembly. Thatvertical compression would not otherwise be available if the lower endof the “stiff” C-shaped spring portion were connected to the footplateat or near its middle, because the patient's weight would not besufficient to overcome that stiffness satisfactorily.

Among its many other benefits, the present invention solves thisproblem, and enables a lower leg prosthesis with only a single mainspring member to store/release vertical loading energy to have both (a)satisfactory control over plantar flexion and/or dorsiflexion and (b)satisfactory vertical spring action. Although the singleenergy-storing/releasing spring member preferably is fabricated in amanner similar to that discussed above and otherwise has characteristicssimilar to at least some of the spring members discussed above, it maybe any of a wide range of different elements, including certain priorart spring components and/or devices.

A convenient analogy can be drawn between certain preferred performancecharacteristics of various embodiments of the invention and a swimmingpool diving board (as noted above, the use of this term “diving board”to describe certain preferred aspects of various Single C-Springembodiments is similar but not necessarily identical to the connectorelement discussion above regarding Double C-Spring embodiments).

In many swimming pool diving boards, the “springiness” of the board canbe adjusted, such as by horizontally repositioning a bar under the boardwithin a range of positions from nearer the “pool end” of the board tonearer to the “steps end” of the board. The bar functions as a pivotpoint for the board. Ifthat pivot point is moved closer to the “poolend” of the board, it shortens the “bendable” portion of the divingboard, making the board feel stiffer. Ifthat bar/pivot point instead ismoved closer to the “steps end” of the board, it lengthens the“bendable” portion of the diving board, and makes it easier for thediver to bend the board, at least in part because the diver's weight isapplied at the end of a longer effective lever arm. In other words, forthe same diver, having the same weight, and jumping on the same locationat the end of the board with the same force, the amount of boarddeflection and the “smoothness” during its bending can vary simply bymoving that bar/pivot point.

Analogously to such swimming pool diving boards, in certain embodimentsof the invention the “springiness” experienced by the patient (again,for the same patient weight, the same loading conditions, etc.) can bemodified by moving its pivot point further toward or away from the toeof the prosthesis. In the embodiments described here, moving that pointfurther toward the toe increases the effective length and thespringiness of the prosthesis' “diving board,” and moving it furtheraway from the toe reduces that springiness. Like the increased “springysoftness” of the diving board when it is set to give the swimmer/diver alonger lever arm, the preferred relatively longer effective length ofthe patient's lever arm (for actuating the main spring body of the Cmember) provides a desirable increase in the “springy softness” of theprosthesis, as experienced by the patient during vertical loading andother situations. Depending on the patient, the patient's expectedactivity level, and other factors, an embodiment of the invention can bedesigned, selected, and/or assembled that provides the performancecharacteristics desired by that patient.

These benefits of moving forward that pivot point are illustrated inFIGS. 5a, 5b, and 5c . At midstance, the patient's weight is directedstraight down, as indicated by weight line C. To illustrate thisanalogy, two “diving board” diagrams are shown on top of the Single-Cembodiment of the invention. Persons of ordinary skill in the art willunderstand that these diving board diagrams are for illustration only,and are not part of the actual embodiments of the invention that arebeing described.

In this analogy, arrow C shows the patient standing at the end of theswimming pool diving board(s) A and B. He/she is ready to jump into thepool, which is located to the left side of line/arrow C (although theprosthesis is shown with the patient facing to the right, this swimmingpool diving board analogy involves the patient jumping off the “divingboard” toward the left side of the drawings). The fixed end of therespective “diving boards” A and B (where the steps to climb up onto thediving board would be located) are to the right side of line C. Tovisually represent the effects of relocating the pivot point from A to B(or vice versa), the Figures show a preferred location for the lower endof the Single Spring member (shown as just the end of that Single Springmember, in the area of line A), and also shows that same Single Springmember if it were pivoted to be “directly connected” to the middle areaof the footplate (this configuration is fully illustrated, with the endof that Single Spring member, in the area ofline B). Preferably, SingleSpring embodiments locate the pivot point at the lower end of theC-shape rightward (toward the prosthetic toe) sufficiently to enable thepatient to readily generate and experience desirable verticalcompression within the C-shape. Using the example illustrated in thedrawing, the effect of moving that pivot point to location A fromlocation B is to lengthen the “diving board” leverage provided to thepatient. As reflected in a comparison of the two “diving boards” A andB, the patient has a much improved springiness and overall experience onthe longer “diving board” A (i.e., when the pivot point for the C-shapedspring member is located near A rather than near B).

For any of these single-C spring embodiments, preferably the toe loadingcharacteristics (on the toe portion of the footplate) are identical orsubstantially the same in midstance, regardless of the length of the“diving board”. By providing the longer “diving board” (moving the pivotpoint to the right), however, the vertical compression of the prostheticapparatus is greatly improved. The patient can more easily store/releasevertical energy (in the main body of the C-shaped element) when providedthat longer lever arm of the longer “diving board”.

Such a “directly connected” C-shaped spring that was sufficiently stiffto handle a full toe load that the patient could be expected toexperience (in the toe-off position, for example) would provide little,if any, vertical compression at mid-stance. Estimating the actualdimensional differences within a relatively standard-sized embodiment ofthe invention, the “diving board” if the pivot is at location B would beshorter than the location A diving board, by around two inches. This notonly would substantially reduce the effective “springiness” experiencedby the patient, but because the effective toe lever also would belonger, the toe portion of the footplate would have to bethickened/stiffened to preserve proper toe stiffness. Consequently, thefootplate would be heavier (generally a negative for lower legprostheses) and would be less able to provide the “soft” springresponses that could be achieved with a less thick toe portion.

Extension Support (Swept Back/Z-Bar/Other)

This desirable “forward positioning” of the prosthesis' spring pivotpoint can be accomplished in any suitable manner. Two of the manyalternative ways to “extend” the pivot point toward the prosthetic toearea are illustrated in the drawings, as a “swept-back” portionintegrally formed at the lower end of the C-shaped spring, and as aseparate “Z-bar” member connecting the Single Spring to the footplate.Both of these approaches preferably provide a relatively stiffconnection between the “forward” pivot axis location and the footplate,to enable the patient to control the footplate. Also preferably, bothapproaches also provide at least some additional energystoring/releasing action within their respective “swept-back” and“Z-bar” structures, and therefore are able to provide additionalopportunities to a prosthetist to fine-tune or adjust the dynamicperformance of the prosthesis.

By way of comparison, in the Double C-spring approach described above(using Spring 1 and Spring 2 in a single prosthetic assembly), theattachment points (for both the upper and the lower ends of Spring 1 andSpring 2) do not have to be as far forward as with Single Springembodiments. The multi-spring embodiments instead preferably provide thedesired vertical performance by simply making Spring 1 less stiff andmore flexible (and relatively “thinner” and lighter), and preferablyproviding the desired toe action and footplate control, etc. via Spring2.

The “swept back” structure is illustrated in FIG. 3f as a relativelytight backwards C curve or downward bend formed near the lower front endof the main body of the C-spring element. From that nearly 180-degreebend, the “swept-back” portion extends back and downwardly to attach tothe middle area of the footplate. As with the other components of theinvention, the “swept-back” and “Z-bar” structures can be fabricatedfrom any suitable material and via any suitable process. Preferably, the“swept-back” portion is fabricated as an integral part of the Single CSpring, from the same types of materials and processes, and thereforegenerally possesses the same or similar energy storing/returningfunctionality as the rest of the “C” member.

The “Z-bar” structure is illustrated as a relatively flat memberextending between approximately the middle of the footplate forwardlyand upwardly to the area of the front pivot point for the C-shapedspring. In the embodiments shown in the drawings, the ends of the Z-barare slightly angled with respect to the body portion of the Z-bar, tohelp align those ends with the respecting confronting surfaces to whichthey are to be attached.

Persons of ordinary skill in the art will understand that preciseshapes, sizes, orientations, and performance characteristics of the“swept back” and/or Z-bar or similar structures/extensions can varywidely depending on the application and the desired performance of theC-spring element and the overall prosthetic assembly. Further, personsof ordinary skill in the art will understand that the connections to thefootplate (and to the Single C-Spring in the case of a Z-bar typeextension) can be accomplished by one or more bolts (as shown), by glueor adhesive, or by any of a wide range of alternative methods and/orapparatus.

Preferably, the Swept-back or Z-bar portion of this type of Single Cembodiment is relatively stiff, but has some flexibility. In certainembodiments, these portions of the prosthesis or prosthetic assembly canbe stiffened (relative to other parts of the prosthesis) by adding fiber(e.g., 3-4 plies) at those locations prior to impregnating the fibersand molding the part(s), although other embodiments may have no such“extra” plies. Persons of ordinary skill in the art will understand thatany other suitable method of adjusting or affecting the springcharacteristics of the extension components (and/or the overallprosthesis) may be used.

In embodiments of this type, the effective pivot or loading length ofthe “heel” (for at least certain aspects of the prosthesis' dynamicloading and performance, etc.) is longer than just from its preferredconnection point near the middle of the footplate back to the rear-mostportion of the footplate. Because these embodiments preferably move theeffective pivot point forward (ahead of the point at which the extensionelement is actually attached to the footplate), the effective length ofthe “heel” preferably is likewise extended, so that it runs from near orat the forward-most portion of the Swept-back or Z-bar extension elementto the farthest-back portion of the footplate. That extra lever armlength provides many benefits in comfort and performance and ease-of-useof the prosthesis, but it also makes it much easier for the patient tocompress the heel (the patient has increased leverage to bend the heelportion). Accordingly, in order to prevent excessive heel compression,the overall stiffness of that lever arm (and the components of it, suchas the Swept-back or Z-bar and the rear portion of the footplate)preferably is designed and selected to provide the desired range ofcompression for the patient, but to not be so flexible as to make theheel too soft. Persons of ordinary skill in the art will understand thatthis stiffness can be customized to meet a variety of factors, includingthe patient's weight and activity level, and others, and that theinvention lends itself to a modular approach that allows readyinterchange of components having different characteristics, dimensions,etc.

Generally, in this type of embodiment of the invention, the furtherforward the pivot point for the main vertical spring, the more of themain body of the C-shape is available to provide the desired energyfunction for vertical and other loads and the more leverage the wearerhas to smoothly load and unload that Single Spring. For example,connecting the lower end of the C Spring directly to or near theforward-most end of the footplate's toe portion would provide themaximum vertical spring action for a given set of prosthetic elements.

However, such embodiments would have several drawbacks. Among otherthings, the further that the pivot point is moved toward the toe, thethicker and heavier the associated forward footplate portions and theconnecting bolts or other hardware would have to be (to withstand thegreater forces imposed by the loading on those effectively longer leverarms). This weight increase would not only make the prosthesis lesscomfortable for the wearer, the concentration of that weight toward theprosthetic toe might impose on the wearer some uncomfortable bendingforces (such as via the wearer's socket, for example). In addition, thatincreased size and component position would make it more difficult oreven impossible to fit the prosthesis into a shoe.

In addition, the further forward the pivot point, the less the effectivelever arm for any toe flexing. This can be desirable to a certainextent, including because the less leverage that the toe portion of thefootplate has (in front of that pivot point), the less strong and lessmassive the toe portion of the footplate needs to be. However, if thepivot point reached or extended past the end of the toe, there would beno desirable toe roll-up or other desired toe action.

Accordingly, in preferred embodiments, including those that use eitherthe swept-back and Z-bar approaches, the pivot point is sufficientlyrearward of the toe end that it allows the toe portion of the footplateto function properly, such as by allowing the toe portion to roll-upduring toe load/toe off. Preferably, the toe portion of the footplate istapered and can “curl up” as the toe load increases, and that curlingmovement shortens even further the effective length of the toe's leverarm (with respect to the pivot point), but still provides at least somedesirable degree of toe roll-up.

Persons of ordinary skill in the art will understand that much of thediscussion above regarding heel strike, mid-stance, and toe-off alsoapplies to single C-spring and other embodiments of the invention. Beloware some additional comments specific to such single C-springembodiments. Exemplary drawings of each of these positions are shown inFIGS. 4a, 4b , and 4 c.

Heel Strike

FIG. 4a shows a conceptual view of a Single C Spring embodiment as itmay be positioned during a heel strike condition. The more-forward pivotaxis and the relatively stiff lever arm between the heel and that pivotaxis allows the Single C Spring to help slow and/or limit theplantar-flexion that otherwise would occur as a result of the heelportion of the footplate being pushed upwardly. As the toe portion ispulled downwardly (because of the heel contacting the ground), the stifflinkage between the footplate and that more-forward pivot point tends to“open” the Single C Spring (much like Spring 2 above is “opened” duringheel strike).

Mid-Stance

FIG. 4b shows a conceptual view of a Single C Spring embodiment as itmay be positioned during a mid-stance condition. As indicated above, bymoving forward the pivot point for the lower front lip of the C-shapedspring element, the prosthesis preferably provides springaction/absorption of vertical loading even at midstance, and preferablydoes so with a gentle and gradual spring action within the main body ofthe C-shaped spring and otherwise. As explained above, unlike prosthesesthat align the spring pivot at or near the patient's midstance weightline, the preferred more forward location of the invention provides tothe patient additional “diving board” leverage, making it easier for thepatient to manipulate and use the prosthesis.

Toe-Off

FIG. 4c shows a conceptual view of a Single C Spring embodiment as itmay be positioned during a toe-off condition. In some single-Cembodiments of the invention, the toe portion of the footplatepreferably is relatively soft, so that during toe-off, that toe portion“rolls up” toward the forward-most portion of the Swept-back or Z-bar.Preferably, this mimics the ball of a normal foot, in that the end ofthe toe plate bends upwardly (like a normal big toe during toe-off). Asit does so, and especially if the toe portion collapses all the way intocontact with the lower front lip of the C-shaped spring element, theeffective “pivot” point between the toe and the ground or other surfacecan move away from the front end of the footplate and back towards thecenter of the footplate. In certain preferred embodiments, this cangenerally move that “pivot point” into approximate vertical alignmentwith the forward-most portion of the Swept-back or Z-bar. The resultingsensation and performance in this position mimics that of a normal foot,in that the patient's sensation that the vertical load line is at ornear the “ball” of the foot, and the C-shaped element preferably is alsoable to provide a desired amount of vertical compression (as would anormal human ankle).

Thus, these types of embodiments of the invention preferably move the Cmember's main pivot point forward, and preferably also better allow theprosthesis to provide vertical compression and related energystorage/return in many situations. One example is when a patient stepsoff a curb and onto the street on the patient's prosthesis. In suchsituations, the patient's weight can be imposed on the prosthesis in asubstantially vertical, downward direction. Ifboth the heel and toe ofthe prosthesis contact the street at generally the same time, anyplantar flexion and/or dorsiflexion forces tend to offset each other, sothat the preferred flexible spring action of the heel/toe portions ofthe footplate are inoperable—the entire footplate stays relatively flat.This leaves vertical weight loading (such as the patient's weight ashe/she steps down onto the street) to be absorbed or cushioned (if atall) by other parts of the prosthesis. By moving the pivot pointforward, these embodiments of the invention allow the main body of the“C” shaped element to compress and cushion the impact from that verticalloading.

Said another way, the invention preferably avoids “locking” the C-shapedspring into a stationary position over the flat toe/heel footplate atmidstance. Instead, these embodiments of the invention pivot from thefront pivot location (toward the toe), and thus provides some vertical“give” even if the toe/heel of the foot portion are relatively “fixed”.On a related point, the Swept-back or Z-bar or other extension membersnot only provide a longer “diving board” (for energy storage/releasewithin the main body of the C member), those members also preferablyprovide some desirable amount of vertical give and/or flex within themembers themselves, allowing further fine-tuning and improvement of theperformance of the prosthesis and the experience of the patient.

Persons of ordinary skill in the art also will understand that movingforward the pivot point allows the main body of the C-shaped spring tobe longer and larger than it otherwise would be. This aids in providinga much gentler and more gradual (and natural) spring action undervertical loading.

Connector

Persons of ordinary skill in the art will understand that the prostheticinventions described herein can be operably connected to a wearer'sstump/socket via any suitable means. Further, while a number ofdifferent connector element variations/versions are shown throughout thedrawings, these are not delimiting, and at least generally may be usedwith single or multiple C-Spring assemblies. FIG. 9 illustrates apreferred embodiment of the invention using an Upper Connector 35 toconnect the preferred elongated energy storing and releasing elementswith a prosthetic socket or other similar structure, in which the UpperConnector preferably includes one or more of the following features:

a swivel dome Lower Interface 115 between the Upper Connector 35 and theone or more generally C-Shaped Spring elements: Preferably, thisinterface is fully articulating and provides convenient adjustment insubstantially any direction (including rotating the prosthetic toe tothe wearer's left or right). The swivel dome structure preferablyfunctions as a partial ball and socket connection. The interfittingdomed interfaces 115 a, 115 b (one concave and one convex) can be formedand assembled in any suitable manner. Among other approaches, the domedshapes can be formed integrally with the Upper Connector and thegenerally C-Shaped Spring elements, or can be formed separately andaffixed/attached to those components. Incorporating the interfaceintegrally into the Upper Connector may be less expensive and easier toassemble than making and using separate parts to form the interface. TheLower Interface elements (the ball/socket parts) could be reversed fromthe arrangement shown in the drawings (with the socket positioned on theSpring element, instead of on the Upper Connector). Preferably, thisallows easy multi-axis adjustment and positioning of the prosthesis.alternatively, instead of a multi-axis dome adjustment, a single plane(forward/back, or Flex/Extend) curved interface: This would provideadjustment of only the forward-back alignment of the prosthesis withrespect to the socket.a Socket Interface 45 having a trough-like shape that conforms at leastgenerally to the anterior surface of a wearer's socket. Preferably, the“trough” portion of the Socket Interface allows it to be positionedvertically at any of a wide range of vertical positions on the generallyfront surface of the socket, thereby providing an independent heightadjustment for the prosthesis with respect to the patient. The trough isshaped to allow the wearer's main socket to be positioned up or down asneeded. Preferably, the lower end of the vertical socket position iswhen it nears contact with the C-Spring member during compression ofthat Spring.especially for Single Spring embodiments, the Lower Interface of theUpper Connector is positioned relatively forward of the wearer's “weightline” and/or near the lateral position of the prosthesis' toe(consistent with the “further forward” pivot axis discussed above)It is modular, and can be readily used for one spring member, two, ormorePreferably, the Upper Connector can be filament wound, and/or hand layupof resin-impregnated graphite fiber. Alternatively, it can be fabricatedfrom aluminum or other suitable material.preferably a single bolt 105 and nut 110 combination holds together theLower Interface elements in a desired position. Consequently, the jointpreferably can be readily adjusted by loosening and tightening a singlebolt. Persons of ordinary skill in the art will appreciate that thenumber of bolts (or other connecting elements) at each of the variouslocations (footplate to Spring 1, for example) can be one, two, or more.For the preferred swivel connector joint at the upper ends of theC-shaped spring elements, a single bolt allows the desiredadjustability.

Filament Winding Fabrication of Spring Members and/or Other Elements

Although the energy storing and releasing C-shaped spring element(s) ofthe invention can be fabricated using any suitable method, theypreferably include one or more of the following features that enablethem to be manufactured using filament winding or other automatedprocesses (which can be much less labor-intensive than manual layup orother processes):

-   -   1. A substantially continuous curve. Preferably, the element has        a generally C-shaped profile in elevation, with no substantial        flat spots or areas.    -   2. At least a substantially constant thickness (no significant        tapers), over at least substantially most or all of the        element's length. This feature can be important for maximizing        the value of using a filament winding method of fabrication, but        is not so critical in hand layup, because hand layup allows easy        addition of fiber/plies at desired locations, making it        relatively easy to taper/change the thickness of the spring at        one or more selected locations along the C-curve. Preferably,        the C spring also has a substantially constant width, but the        invention can be practiced without any such constant widths.    -   3. No tight or sharp corners within the curve. The curve can be        a substantially constant radius or not, and can be symmetrical        or not.    -   4. No undercuts or indentations along the curve. Instead, it is        substantially continuously concave (or convex, depending on your        perspective). Filament winding typically is not able to force        the filament down into a “low spot”; instead, the fibers will be        stretched tautly across that low spot, and consequently the “low        spot” will NOT be part of the piece being formed. A similar        concept applies to sharp corners: even though the corner may NOT        technically be an undercut, filament winding likely would pull        the filament at those corners more tightly than in the areas        between such corners. As a consequence, the finished part would        have thicker side areas as compared to those “more taut”        corners.

The foregoing features (alone and/or in combination) provide severaladvantages to the invention, including facilitating fabrication of thepreferred C-spring element(s) using an automated process such asfilament winding. However, as noted elsewhere the elements can be madevia any suitable process, including conventional hand layup processes.

One benefit of using filament-winding or similar automated processes isreducing the costs and time needed for fabricating the element(s). Amongother things, such machine processes avoid the labor- and time-intensiveprocess required for hand layup of such parts. Such automated processesalso can provide good quality control in the resultingenergy-storing/releasing members.

Any suitable filament-winding technique(s) can be used to fabricate theenergy-storing/releasing members 5 of the invention. FIGS. 6a-6lillustrate one example of how filament winding might be used inpracticing the present invention. Filament winding of resin-impregnatedfiber parts commonly uses a hollow mandrel that is spun on its axis.Mandrels can be provided in a wide range of sizes and shapes, includingones suitable for fabricating the C-shaped spring energy storing andreleasing elements of the invention. Mandrels for filament windingcommonly are about two feet or more along the spinning axis.Accordingly, and as described herein, a single mandrel can be used tofabricate one or many energy storing and releasing elements during asingle filament-winding process cycle.

The energy-storing/releasing C-spring members of the invention can beprovided in a wide range of shapes and sizes. Depending on their preciseconfiguration and other factors, filament winding can be used tofabricate them individually or “in bulk”. As an example, it can beconvenient and economical to filament-wind them on a generallycylindrical mandrel, forming a corresponding cylinder around most or allof the length of the mandrel. After the wound cylindrical piece hashardened, the individual C-spring elements can be cut from it. Forexample, the cylinder can be cut into separate hoops of a desired width(e.g., two-inches wide). From each such hoop, preferably at least twoseparate energy-storing/releasing members of the invention can be cut(if the energy-storing/releasing C-spring member is to have an arc ofmore than 180 degrees, only one C-spring can be cut from each ring). Atsome appropriate stage of the process, some or all of the part can befurther custom-shaped, if desired. For example, the ends of the C-shapedspring elements can be smoothed and rounded, to avoid poking or damagingnearby persons.

As indicated, the preferred energy-storing/releasing C-spring members ofthe invention do not have any specially “thickened” portions or areas,but instead have a relatively constant thickness along the entirearcuate length of the member. This provides a number of benefits, inaddition to enabling the part to be fabricated more efficiently. Forexample, the preferred relatively constant thickness helps ensure asubstantially smooth “load/unload” action during use of the prosthesisor other device in which the energy-storing/releasing member is used. Inother words, the energy that is required to compress or expand orotherwise deform the generally C-shaped element(s) from its restingposition preferably is gradual and smooth, and has no sudden or sharpchanges, through the full range of the intended compression/expansionmovement of the member. Similarly, the return forces and motion (as theload is released from the member) preferably is gradual and smooth.Thus, the energy-storing/releasing element itself preferably imposesvery little, if any, sudden stress/loading changes on the patient or therest of the assembly as it is deformed and as it springs back to itsresting position.

Said another way, the bending forces and characteristics preferably arerelatively consistent and/or dispersed along most or even the entirelength of the energy-storing/releasing element(s). The preferredthickness and shape of the energy-storing/releasing members of theinvention helps distribute the energy storing and releasing action overmost or substantially all of the element (rather than loading someportions of the member more heavily than other portions).

For the purpose of summarizing the invention, certain objects andadvantages have been described herein. Itis to be understood that notnecessarily all such objects or advantages may be achieved in accordancewith any particular embodiment of the invention. Thus, for example,those skilled in the art will recognize that the invention may beembodied or carried out in a manner that achieves or optimizes oneadvantage or group of advantages as taught herein without necessarilyachieving other objects or advantages as may be taught or suggestedherein.

The apparatus and methods of the invention have been described with someparticularity, but the specific designs, constructions, and stepsdisclosed are not to be taken as delimiting of the invention. A widerange of modifications and alternative structures and steps forpracticing the invention will make themselves apparent to those ofordinary skill in the art, all of which will not depart from the essenceof the invention, and all such changes and modifications are intended tobe encompassed within the appended claims.

1-55. (canceled)
 56. An energy-storing and energy-releasing prostheticpylon, said pylon including: a C-shaped portion, said C-shaped portionan open portion of the C facing anterior toward an amputee's toe regionand a closed portion of the C facing posterior toward an amputee's heelregion; said C-shaped portion having a substantially continuous modulusof elasticity along its length, said length storing and releasing energyupon loading and unloading by its wearer during ambulation or othermovement or use, said substantially continuous modulus of elasticityproviding a generally equal capacity for spring action in an upper halfof said C-shaped portion as for a lower half of said C-shaped portion,said pylon connected to a socket, said C-shaped portion with saidsubstantially continuous modulus of elasticity including an uppersection within an upper half of said C-shaped portion, said uppersection being anterior of a most distal anterior surface of said socket,said upper section not prevented from flexing movement by saidconnection between said pylon and said socket.
 57. A prosthetic lowerleg including: At least two C-shaped spring elements, each having anupper end and a lower end, each spring element having a respective openportion where the C-shapes face forward with respect to an intendedpatient, said spring elements configured to cooperate with each other asthe only elements, at least between said respective upper ends and saidrespective lower ends, for transmitting mechanical forces between apatient's socket and a ground contact point of the lower limb device,said spring elements operatively connected at their upper ends to saidsocket at a location that is both (a) anterior of a patient's weightline and (b) at a position at or anterior of a most distal anteriorsurface of the socket.